Many technical and industrial operations employ aqueous acid solutions which come in contact with metal surfaces. In such operations, the metal surfaces in contact with the acidic solutions generally are corroded by those solutions if preventative measures are not taken.
The types of acidic solutions encountered during refinery operations varies. For example, in many product streams, hydrochloric acid is encountered in the hundreds of parts per million. At such low concentrations, the corrosive activity of the hydrochloric acid may be controlled easily and economically by adding a nuetralizer to the product stream.
Occasionally, a refinery may be required to process crude oil which liberates a high concentration of carbon dioxide when heated, e.g., if carbon dioxide flooding was used to liberate the crude oil, or if the crude oil contains a high concentration of naphthenic acids. When such crude oil is processed, the carbon dioxide levels in the resulting product streams also may be high. As a result, the metal surfaces of the processing equipment may be corroded by the carbonic acid formed when the carbon dioxide dissolves in the solution.
The amount of carbon dioxide present in such situations is much greater than the amount of hydrochloric acid present in most refinery operations. Therefore, because of the volume of neutralizer that would be required, it would not be economically feasible to prevent corrosion by carbonic acid in such situations. Therefore, methods and compositions which would economically and effectively inhibit such corrosion would be highly desirable.